Method for operating a weaving and shedding machine

ABSTRACT

The object of the invention is to optimize the electromotive driving and braking moments or torques required in the starting and braking phase of the weaving and shedding machine while reducing the mechanical loading or stressing of machine elements of the shedding and weaving machine and while preventing starting marks in the woven fabric, and on the basis thereof, to achieve so-called soft starts and soft stops, in particular, of the shedding machine. The object is achieved according to the invention in that, in a weaving machine equipped with an electromotive main drive and in a shedding machine equipped with an electromotive auxiliary drive, the shedding machine is started at a time point (t1) that lies before the starting time point of the weaving machine, and in that, upon a triggered interruption of the weaving process, the shedding machine comes to the standstill at a time point (t5) that lies after the standstill time point (t4) of the weaving machine.

[0001] The invention relates to a method for operating a weaving andshedding machine according to the features of the preamble of Patentclaim 1.

[0002] A drive arrangement is known from the EP 0,893,525 A1, whereinthis drive arrangement consists of a weaving machine, which possesses adrive motor as a main motor, and of a shedding machine with a drivemotor as an auxiliary motor, as well as a control device.

[0003] The control device is connected in a signal transmitting manneron the one hand with the main motor of the weaving machine, and isconnected in a signal transmitting manner on the other hand with thedrive of the shedding machine embodied as an auxiliary motor. Aregulating unit integrated in the control device pursues a regulationstrategy, whereby on the one hand the weaving machine and the sheddingmachine are operated essentially synchronously at their start up, and onthe other hand the shedding machine is operated with a predeterminedrotational speed fluctuation during the weaving operation, whereby thisrotational speed fluctuation lies within the rotational speed toleranceof the weaving machine.

[0004] The previously known drive arrangement has the disadvantage, dueto the synchronous operating manner of both drives, that a beating-up ofthe weaving reed against the binding or interlacing point of the wovenfabric takes place per revolution of the weaving machine main shaftduring the starting phase. In this case, an undesired compressing orcompacting of the woven fabric without a weft thread insertion ispracticed, for example during five revolutions of the weaving machinemain shaft, identical to five weaving cycles or five beat-up strokes ofthe weaving reed against the interlacing point of the woven fabric.Moreover, the beating-up of the weaving reed without weft threadinsertion leads to a so-called micro-roughening of the weft and warpthreads at the interlacing point of the woven fabric. For example duringthe dyeing of the produced woven fabric, the micro-rougheningretroactively leads to an apparent weaving fault or defect, becausecomparatively more dye will be taken up both by the compressed orcompacted woven fabric section as well as by the roughened weft and warpthreads, than by the remaining woven fabric.

[0005] A grave disadvantage of the previously known solution is that thesynchronous manner of operating the drives in the starting phase butalso in the braking phase of the weaving and shedding machine leads toan increased loading or stressing of the machine elements and driveelements in comparison to the weaving process. The increased loading orstressing, of which the cause lies in the prescribed starting or run-upbehavior of the weaving and shedding machine, as a consequence requiresa corresponding design of the electromotive drives with respect to powerconsumption, rotational moment or torque, etc., and a correspondingdimensioning of the applicable machine parts and elements.

[0006] It is the object of the invention, to optimize the electromotivedriving torques and braking torques required in the starting and brakingphase of the weaving and shedding machine while reducing the mechanicalstress or loading of machine elements of the shedding and weavingmachine, and while preventing starting marks in the woven fabric, andbased thereon, to achieve so-called soft starts and soft stops, inparticular, of the shedding machine.

[0007] According to the invention, the object is achieved with thefeatures of the Patent claim 1.

[0008] A first essential feature according to the invention is that theshedding machine is started in a freely programmable manner within atime window Δt1 before the weaving machine, and that the weaving machineis only started after the running-out or expiration of the time windowΔt1, at a later time point t2. Connected therewith is the advantage thata lower drive moment or torque of the electromotive drives, incomparison to the prior art, is required in the starting phase of theweaving and shedding machine. A further decisive advantage is that theweaving reed of the weaving machine carries out no reed beat-ups againstthe beat-up edge of the woven fabric or against the interlacing point ofthe woven fabric in the starting phase of the shedding machine, andthereby so-called starting marks, as a cause of reed beat-ups withoutweft threads, are avoided.

[0009] A second essential characteristic feature according to theinvention exists in that, after a prescribed progress or execution ofthe starting processes, the shedding and weaving machine are operatedapproximately synchronously at a time point t3. This means that, in ashedding machine embodied as a heald or dobby weaving machine or ajacquard weaving machine, the run-up (starting phase) at first can becarried out without movement of the shedding means, and thepattern-controlled movement of the shedding means is added-on beginningonly in the phase of the synchronous operating manner of both machines.Thus, in the starting phase of the heald or dobby machine and thejacquard machine, only the masses of the shedding machines by themselvesare accelerated, while the shedding means in the weaving machinepreferably are located in a shed open position.

[0010] A third characteristic feature exists in that the synchronousoperating manner of the weaving and shedding machine is terminated inconnection with a signal detecting the operational interference ormalfunction of the weaving and/or shedding machine. Thereupon, thebraking process is initiated for both machines, and namely by a fourthessential characteristic feature according to the invention, whichconsists in that both machines come to the standstill at different timepoints after the initiation of the braking process, whereby the sheddingmachine comes to the standstill according to the invention at a freelyprogrammable time point within a time window Δt2 after the standstilltime point t4 of the weaving machine. In this manner it can be providedaccording to the invention, to operate the drives in the manner of agenerator as of their braking time point until the standstill timepoint, while these function in the manner of a motor in the starting andsynchronous running phase. Connected with the operating manner as agenerator, is the advantage that the clutch-brake combinations used inweaving machines can be omitted or avoided. The kinetic energy of theweaving and shedding machine is thus not nullified essentially throughclutch-brake combinations, but rather is converted into useable energy,for example being fed back into the power grid.

[0011] Further embodiment features of the invention and advantageouseffects connected therewith arise from the dependent claims.

[0012] In the following, the invention is described in further detail inan example embodiment.

[0013] In the schematic illustration, also see the Figure, the operatingcourse or sequence, according to the invention, of a weaving andshedding machine is illustrated in connection with the loom shedformation carried out by the shedding machine, whereby the weavingmachine possesses an electromotive drive as a main drive and theshedding machine possesses an electromotive drive as an auxiliary drive.

[0014] As shown on the left side in the schematic illustration, as isgenerally known, the process for forming a loom shed for the purpose ofthe picking or insertion of at least one weft thread and for the purposeof interlacing or binding-in the at least one weft thread, consists of:

[0015] a) the opening of the loom shed,

[0016] b) the shed standstill (here the at least one weft thread isinserted into the loom shed) and

[0017] c) the closing of the loom shed.

[0018] As already described above, according to the prior art, thestarting process of both machines is carried out synchronously,independently of whether the weaving machine and the shedding machineare started with a common electromotive drive or with respectivelymutually independent electromotive drives. The weaving and machinetechnological disadvantages that arise thereby are known.

[0019] The known solution to operate the weaving machine with anelectromotive main drive and the shedding machine with an electromotiveauxiliary drive offers the possibility according to the invention, tostart the shedding machine before the weaving machine. In the schematicillustration, the starting time point t1 of the shedding machine is setaccording to the invention so that the shedding machine is startedbefore the starting time point t2 of the weaving machine. In thiscontext, the time point t1 of the start of the shedding machine can befreely programmably selected within the time window Δt1. The start ofthe shedding machine could lie, for example, 60 ms before the start ofthe weaving machine. The time window Δt1 corresponds to the presentexample embodiment Δt1=c+b/2. Stated differently, Δt1 corresponds toapproximately 180 rotational angle degrees of the weaving machine mainshaft, if a corresponds to approximately 90, b corresponds toapproximately 180, and c corresponds to approximately 90 rotationalangle degrees of the weaving machine main shaft.

[0020] The schematic illustration further shows that the weaving machineis started after completion or expiration of the time window Δt1, andnamely at a time point t2, which is different from t1. It is importantin this regard, that the time points t1 and t2 to be programmed nevermay be identical, but rather must lie so far apart from one another,that a synchronous operating manner between the shedding machine and theweaving machine exists only upon a shed closing that takes place afterthe start of the shedding machine and the weaving machine, namely at thetime point t3.

[0021] The synchronous operating manner of both machines is terminatedupon or in connection with an electrical signal detecting an operatinginterference or malfunction in the weaving or shedding machine, forexample upon or in connection with a signal detecting a weft threadbreak. Thereupon it is provided according to the invention, that theshedding machine comes to a standstill at a time point t5 that is freelyprogrammable within a time window Δt2 and that is after the standstilltime point t4 of the weaving machine. With reference to the weavingmachine main shaft, the later standstill corresponds to, for example,180 rotational angle degrees of the weaving machine main shaft after itsstandstill. For the renewed start, for example after the weft threadbreak is removed or cleared, the shedding machine is brought into thestarting position, which corresponds to the time point t1. Thereby, theshedding machine is once again situated in a position which enables theinventive operating manner of the shedding and weaving machine.

[0022] In comparison to the prior art, the inventive operating mannerleads to the above mentioned quality improvement in the woven goods,namely the most substantial or extensive avoidance of starting marks,because the shedding machine starts independently of the start of theweaving machine. Thus, no reed beat-ups are realized outside of thesynchronization of the weaving machine and the shedding machine.

[0023] It is further advantageous, that the weaving machine alwaysstarts with the same mass conditions, that is to say the binding orweaving, or respectively the lifting or removal of the jacquard machinehas no influence on the run-up behavior of the weaving machine.

[0024] The independence of the electromotive drives of the weaving andshedding machine makes it possible in an advantageous manner to vary theshed closing, weft pick for weft pick, during the running operation ofthe machine, whereby the quantity of weft thread waste can be reduced.

[0025] Furthermore, with the separated arrangement of the weavingmachine drive and the shedding machine drive, the possibility is opened,for jacquard machines of simple construction type, which have noeccentric controlled loom shed formation, but rather a crank drive, torealize a longer shed standstill by means of rotational speed variationof the electromotive drive, which is advantageous especially for weavingmachines with mechanical weft thread insertion means (grippers).

1. Method for operating a weaving and shedding machine, whereby theweaving machine is equipped with an electromotive main drive and theshedding machine is equipped with an electromotive auxiliary drive,wherein the electromotive main drive and the electromotive auxiliarydrive is actuated in a signal transmitting manner with a control device,wherein the weaving machine and the shedding machine is brought from thestandstill to a prescribed rotational speed, and wherein, upon anoccurring interference, the weaving machine and the shedding machine areshifted into the standstill by braking means, characterized in: that theshedding machine is started within a time window Δt1 before the weavingmachine, that the weaving machine is started after expiration of thetime window Δt1 at a time point t2 lying outside of the time window Δt1,that the shedding machine and the weaving machine, after their startingprocess, are operated approximately synchronously as of a fixable timepoint t3, that the synchronous operating manner of the weaving andshedding machine is terminated upon an electrical signal detecting anoperating interference, and that thereupon the braking process for theweaving and shedding machine is initiated in such a manner, that bothmachines come to the standstill at different time points.
 2. Methodaccording to claim 1, characterized in that the starting time point ofthe shedding machine is freely programmable within the time window Δt1.3. Method according to claim 1, characterized in that the starting timepoint t2 of the weaving machine lies before the synchronization timepoint t3 of the shedding and weaving machine.
 4. Method according toclaim 1, characterized in that the weaving machine comes to thestandstill at a time point t4, which lies before the standstill timepoint t5 of the shedding machine.
 5. Method according to claim 4,characterized in that the standstill time point t4 of the weavingmachine lies before the maximum opening of a loom shed for a weft threadinsertion.
 6. Method according to claim 1, characterized in that thestandstill time point t5 of the shedding machine is freely programmablewithin a time window Δt2.
 7. Method according to claim 1, characterizedin that the weaving machine and the shedding machine is driven in themanner of a generator as of their braking time point until theirstandstill time point.
 8. Drive arrangement for carrying out the methodaccording to claim 1, characterized in that the shedding machine is aheald shaft or dobby machine or a jacquard machine.